Aux question.

Have a 04 cts. & Hate that I can't connect my phone to an aux cord. I remember my cousin having a aux cord on his super old car but the cord ran from like the feet area. Was wondering if there's any way I can get a aux I stalled? Without getting like a custom stereo. I live in Dallas having stuff like that is pointless because it will just get stolen. HELPPPPP. Tired of burning/buying CDs for my car. Lol